Ghostlore

The glyph grid shows up when you open the inventory screen (I on keyboard). It starts with a small amount unlocked and as you level up you get 1 square per level. It is fully unlocked at level 50. Compounds glyphs take 5 spaces each, so you must reach level 50 to unlock this. Basically you need every square of the glyph grid covered by compound glyphs. Regular glyphs only take up one square and do not matter for this achievement.

Each compound glyph has a shape and it cannot be rotated. There is a shop in town that can randomize the shape for 10 demon blood (use alkahest on either type of glyphs) and 2000 gold. Since you only get 1 demon blood for each glyph you break down, the best thing to do is stash as many compound glyphs with different shapes as possible so when you hit 50 you can try to build a full grid. I stashed every compound glyph I got in preparation and even with a full stash (both tabs) and inventory I was missing a few shapes I could have used, so you should really be saving them up to make it easier.